Contact resistance is generated in a terminal at the time of energization, and detection of heat generated due to the contact resistance is effective for preventing damage of an electrical wire, a connector, and the like by overcurrent energization. Therefore, a unit configured to detect a heat generation temperature of a terminal connection point has been proposed (Patent Literatures 1 and 2).
A temperature detection unit 100 of Patent Literature 1 has: a housing part 101 attached to a covering part 112 of an electrical wire W to which a terminal 110 has been connected; and a temperature detection part 102 fixed in the housing part 101, as shown in FIGS. 9 and 10. The temperature detection part 102 has: a melting piece 103 that abuts against the covering part 112 of the electrical wire W through a hole 101a of the housing part 101; and a pair of contact parts 104 and 105 that are elastically bent and deformed by the melting piece 103, and that are thereby brought into contact with each other. A terminal point generates heat by energization of overcurrent, and the generated heat is transferred to a core wire 111 and the covering part 112 of the electrical wire W. The melting piece 103 melts by the generated heat transferred to the covering part 112, and the pair of contact parts 104 and 105 are deformed in elastic restoration directions, and separate from each other. Therefore, energization of the overcurrent is detected, and damage or the like of the terminal 110, the electrical wire W, and the like due to the overcurrent is prevented.
A temperature detection unit 120 of Patent Literature 2 includes: a connector housing 121 inside which a terminal (not shown) is housed; and a thermistor 123, as shown in FIGS. 11 and 12. The connector housing 121 has a sensor housing wall 122 on an opposite side of a side where the terminal has been housed, and the thermistor 123 is housed in the sensor housing wall 122. A terminal point generates heat by energization of overcurrent, and the generated heat is transferred to the connector housing 121. Namely, a temperature by the heat transferred to the thermistor 123 through the connector housing 121 is detected. Therefore, energization of the overcurrent is detected, and damage of the terminal, the connector housing 121, and the like by the overcurrent is prevented.